Electronic controls are well-known in the art. Typically, electronic controls receive analog input signals and produce digital output control signals. These controls are used to control various apparatuses. One such application is in the control of temperature of a zone or a room in a building. A control can be used to detect the temperature and air flow, and is adapted to control motors for fans to circulate the air and to open or close the dampers which circulate the air.
Electronic communication between like controls is also well-known in the art. One such well-known technique of communication is known as the half-duplex mode of communication. In such a communication scheme, one unit, and only one unit, can transmit at a time. To ensure that the transmission of data by a second unit does not begin prematurely while the first unit has not completely terminated its transmission, typical prior art apparatus has used passive RC circuits to determine the end of transmission of one unit, to wait a period of time prior to permitting the second unit to commence its transmission. In such an environment, the communication protocol is not operating in 100% duty cycle.
Programmable gain and offset circuits are also well-known in the art. However, heretofore, a programmable gain and offset circuit has been complete and expensive to make.